A group of scientists have discovered evidence of “the building blocks of life” on the surface of Pluto. Using the Hubble Space Telescope’s Cosmic Origins Spectrograph researchers discovered evidence of complex organic molecules which may be responsible for giving the planet its ruddy color.

Space.com reports that the discovery was made when researchers noticed that a substance on Pluto was absorbing more ultraviolet light than expected.

Study leader Alan Stern, of the Southwest Research Institute in Boulder, Colo., said:

“This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color.”

According to Space.com, Pluto orbits along several other icy objects, which are also red, in what is known as the Kuiper belt. Researchers believe that organic compounds may exist on several objects in the Kuiper belt.

Researchers will be able to get a closer look at Pluto in a few years when NASA’s New Horizon spacecraft visits the dwarf planet.